From e0a3c657ecbd82d1350949704ef9cbd272037566 Mon Sep 17 00:00:00 2001 From: Naidile Date: Fri, 16 May 2025 15:13:33 +0200 Subject: [PATCH] Update README.rst Correcting sentence structure to ease readability Signed-off-by: Naidile --- micropython/umqtt.robust/README.rst | 38 ++++++++++++++--------------- 1 file changed, 19 insertions(+), 19 deletions(-) diff --git a/micropython/umqtt.robust/README.rst b/micropython/umqtt.robust/README.rst index 4c7226d22..1795bf795 100644 --- a/micropython/umqtt.robust/README.rst +++ b/micropython/umqtt.robust/README.rst @@ -16,15 +16,15 @@ there's no power (mains outage or battery ran out). As you may imagine, umqtt.robust won't help you with your flat battery. Most computing systems are now networked, and communication is another weak link. This is especially true for wireless communications. If two of your -systems can't connect reliably communicate via WiFi, umqtt.robust +systems can't connect or reliably communicate over WiFi, umqtt.robust can't magically resolve that (but it may help with intermittent WiFi issues). What umqtt.robust tries to do is very simple - if while trying to -perform some operation, it detects that connection to MQTT breaks, -it tries to reconnect to it. That's good direction towards "robustness", -but the problem that there is no single definition of what "robust" -is. Let's consider following usecase: +perform some operation, it detects that the connection to MQTT breaks, +it tries to reconnect. That's a good direction towards "robustness", +but the problem is that there no single definition of what "robust" +is. Let's consider the following usecases: 1. A temperature reading gets transmitted once a minute. Then the best option in case of a transmission error might be not doing @@ -35,11 +35,11 @@ battery-powered, any connection retries will just drain battery and make device "less robust" (it will run out of juice sooner and more unexpectedly, which may be a criteria for "robustness"). -2. If there's a button, which communicates its press event, then -perhaps it's really worth to retry to deliver this event (a user +2. If there's a button which communicates it's press event, then +perhaps it's really worth it to retry delivering this event (a user expects something to happen when they press the button, right?). -But if a button is battery-power, unconstrained retries won't do -much good still. Consider mains power outage for several hours, +But if a button is on battery-power, unconstrained retries still won't do +much good. Consider mains power outage for several hours, MQTT server down all this time, and battery-powered button trying to re-publish event every second. It will likely drain battery during this time, which is very non-robust. Perhaps, if a press @@ -48,10 +48,10 @@ on what press does, the above may be good for a button turning on lights, but not for something else!) 3. Finally, let's consider security sensors, like a window broken -sensor. That's the hardest case. Apparently, those events are +sensor. That's the hardest case. Those events are important enough to be delivered no matter what. But if done with short, dumb retries, it will only lead to quick battery drain. So, -a robust device would retry, but in smart manner, to let battery +a robust device would retry, but in a smart manner to let the battery run for as long as possible, to maximize the chance of the message being delivered. @@ -61,19 +61,19 @@ a) There's no single definition of what "robust" is. It depends on a particular application. b) Robustness is a complex measure, it doesn't depend on one single feature, but rather many different features working together. - Consider for example that to make button from the case 2 above + Consider for example that to make the button from the case 2 above work better, it would help to add a visual feedback, so a user - knew what happens. + knows what happened. As you may imagine, umqtt.robust doesn't, and can't, cover all possible "robustness" scenarios, nor it alone can make your MQTT application "robust". Rather, it's a barebones example of how to reconnect to an MQTT server in case of a connection error. As such, it's just one -of many steps required to make your app robust, and majority of those +of the many steps required to make your app robust, and majority of those steps lie on *your application* side. With that in mind, any realistic -application would subclass umqtt.robust.MQTTClient class and override +application would inherit umqtt.robust.MQTTClient class and override delay() and reconnect() methods to suit particular usage scenario. It -may even happen that umqtt.robust won't even suit your needs, and you +may even be possible that umqtt.robust doesn't suit your needs, and you will need to implement your "robust" handling from scratch. @@ -82,18 +82,18 @@ Persistent and non-persistent MQTT servers Consider an example: you subscribed to some MQTT topics, then connection went down. If we talk "robust", then once you reconnect, you want any -messages which arrived when the connection was down, to be still delivered +messages which arrived when the connection was down, to still be delivered to you. That requires retainment and persistency enabled on MQTT server. As umqtt.robust tries to achieve as much "robustness" as possible, it makes a requirement that the MQTT server it communicates to has persistency enabled. This include persistent sessions, meaning that any client -subscriptions are retained across disconnect, and if you subscribed once, +subscriptions are retained on disconnectivity, and if you subscribed once, you no longer need to resubscribe again on next connection(s). This makes it more robust, minimizing amount of traffic to transfer on each connection (the more you transfer, the higher probability of error), and also saves battery power. -However, not all broker offer true, persistent MQTT support: +However, not all brokers offer true, persistent MQTT support: * If you use self-hosted broker, you may need to configure it for persistency. E.g., a popular open-source broker Mosquitto requires